add two finger swipe gestures for showing TOC and bookmarks

two_finger_swipe to east is for TOC
two_finger_swipe to west is for bookmarks

frontend/ui/reader/readerbookmark.lua

@@ -18,11 +18,26 @@ local ReaderBookmark = InputContainer:new{
 function ReaderBookmark:init()
 	if Device:hasKeyboard() then
 		self.key_events = {
-			ShowToc = {
+			ShowBookmark = {
 				{ "B" },
 				doc = _("show bookmarks") },
 		}
 	end
+	if Device:isTouchDevice() then
+		self.ges_events = {
+			ShowBookmark = {
+				GestureRange:new{
+					ges = "two_finger_swipe",
+					range = Geom:new{
+						x = 0, y = 0,
+						w = Screen:getWidth(),
+						h = Screen:getHeight(),
+					},
+					direction = "west"
+				}
+			},
+		}
+	end
 	self.ui.menu:registerToMainMenu(self)
 end